1. Field of the Invention
This invention relates to a terminal block for an electrical switching device, and more particularly to an auxiliary terminal block having at least one terminal which locks within a slot of the auxiliary terminal block and terminates the auxiliary wiring of a circuit breaker.
2. Background of Information
Electrical switching devices include, for example, circuit switching devices and circuit breakers. Circuit breakers are generally used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload fault or a relatively high level short circuit condition. Molded case circuit breakers, for example, include at least one pair of separable contacts which may be operated either manually by way of a handle disposed on the outside of the case or automatically in response to an overcurrent condition. In the automatic mode of operation, an electronic trip unit, for example, controls an operating mechanism which opens the separable contacts. In the manual mode of operation, the handle, for example, cooperates with the operating mechanism in order to open the separable contacts.
Electrical switching devices have a line terminal for connection to a power source and a load terminal for connection to a load, such as a motor. The separable contacts of the electrical switching device are internally connected to the line and load terminals. Electrical switching devices may also have one or more auxiliary terminals. In a circuit breaker, for example, such auxiliary terminals may be utilized as inputs to provide an external signal for tripping the circuit breaker. Furthermore, other such auxiliary terminals may be utilized as outputs to externally indicate the trip status of the circuit breaker.
Input auxiliary terminals may include, for example, connections to a shunt trip mechanism or an undervoltage trip relay which trips the circuit breaker whenever the line voltage fall below a predetermined value. An external three-position auxiliary terminal block is utilized to provide two terminals for interconnection of the circuit breaker with such external trip mechanisms. Output auxiliary terminals may include, for example, connections to a bell alarm and other external circuits for enunciating or monitoring the open/closed/tripped status of the circuit breaker. An external three-position auxiliary terminal block is utilized to provide three terminals for interconnection of two circuit breaker status relay contacts having a common reference node with such external status monitoring circuits. Combinations of input and output auxiliary terminals may be provided by auxiliary terminal blocks having plural (e.g., six, nine, etc.) terminals.
Existing auxiliary terminal blocks for circuit breakers include a molded block having a first recess for terminating an external wire to the circuit breaker, a second recess for terminating an internal wire of the circuit breaker, and a partition which substantially separates the first and second recesses. The partition has a rectangular opening which interconnects the first and second recesses.
A generally square terminal having a tapped hole rests in the first recess. The tapped hole accepts a screw terminal assembly which terminates the external wiring. The bottom of the first recess has a recessed hole which accommodates the screw terminal assembly. The square terminal also has a rectangular solder tab attached to one side of the terminal for terminating the internal wire of the circuit breaker. The solder tab protrudes through the rectangular opening of the partition and enters the second recess. The solder tab has a hole which may be centered within the second recess. The bottom of the second recess of the existing auxiliary terminal block is generally open. The internal wire of the circuit breaker is inserted through the top of the second recess and through the hole of the solder tab. The internal wire is soldered to the bottom of the solder tab which is accessed through the open bottom of the second recess.
The terminal block further has two upper removable covers for covering the two recesses at the top of the block. Similarly, the terminal block also has a lower removable cover for covering, at the bottom of the block, the hole of the bottom of the first recess and the open bottom of the second recess.
Although the existing terminal block provides a functional design, there is room for improvement. Accessibility of the solder tab within the open bottom of the second recess is limited. This limited accessibility hinders the quality of the resulting solder connection between the internal wire of the circuit breaker and the solder tab. The limited accessibility also increases the time associated with manufacturing the auxiliary terminal block.
There is a need, therefore, for an auxiliary terminal block for a circuit breaker which improves the accessibility of the termination for the internal wiring of the circuit breaker.
There is a more particular need for such an auxiliary terminal block which maximizes the quality of the connection between the internal wiring of the circuit breaker and the termination.
There is another more particular need for such an auxiliary terminal block which eliminates the requirement of a solder connection between the internal wiring of the circuit breaker and the termination.
There is yet another more particular need for such an auxiliary terminal block which maximizes the quality of a solder connection between the internal wiring of the circuit breaker and the termination.
There is another need for an auxiliary terminal block for a circuit breaker which decreases the manufacturing time required to assemble the auxiliary terminal block.
There is still another need for an auxiliary terminal block for a circuit breaker which permits the termination to be assembled outside of the auxiliary terminal block.